Multilayer ceramic capacitors, multilayer chip electronic components, are chip-type condensers installed on the printed circuit boards of various electronic products, for example, image display devices such as liquid crystal displays (LCDs), plasma display panels (PDPs) or the like, computers, personal digital assistants (PDAs), mobile phones, and the like, to charge or discharge electricity.
Such multilayer ceramic capacitors (MLCCs), having positive attributes such as compactness, guaranteed high capacitance, and ease in the mounting thereof, may be used as components in various electronic devices.
Such an MLCC may have a structure in which a plurality of dielectric layers and internal electrodes are alternately disposed in such a manner that the internal electrodes having different polarities are provided between the dielectric layers.
The dielectric layers have piezoelectric and electrostrictive properties. Thus, when a direct current (DC) or alternating current (AC) voltage is applied to an MLCC, a piezoelectric phenomenon may occur between internal electrodes, thereby causing the occurrence of vibrations.
Vibrations may be transferred to boards on which MLCCs are mounted, through external electrodes of the MLCCs, leading to the entirety of the boards acting as acoustically radiating surfaces to generate vibratory sound as noise.
Vibratory sound may correspond to audio frequencies ranging from 20 Hz to 20,000 Hz, causing listener discomfort, and such a vibratory sound, which may cause listener discomfort, is commonly known as acoustic noise.
As low noise designs of electronic products have come to prominence, acoustic noise generated in MLCCs has become an issue. In particular, reductions of acoustic noise in electronic products having a voice communications function, such as smartphones, have been required.